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Re: [Xen-API] value of timestamp from API event.from() is always '0'




Now my solution is that using two threads, one call event.next() and return immediately, and another deal with the events returned.

So I can get messages with timestamps, but cannot get the events history.

Maybe there is a bug under XenServer 6.2 ?

-----------
Cao Tong

On 09/17/2015 09:42 PM, Dave Scott wrote:
On 17 Sep 2015, at 13:39, Uli Stärk <Uli.Staerk@xxxxxxxxxxxxxx> wrote:

Hey Tony,

I've seen this too. I don't know what the events.from was designed for. I've seen 
XenCenter using it for a "fast"-sync with the pool, and features some kind of 
logging (see id=0, class=message). I think you can safely skip all events with id=0 and 
accept the ts=0 as given :)
I’ve cc:d Jonathan Ludlam, who built the `event.from` mechanism — he can 
probably describe the fine-detail.

The main semantic difference between `event.next` and `event.from` from my point-of-view is 
that `event.next` reads from a fixed-space queue of object state snapshots which can easily 
overflow, while `event.from` fetches the *current* state of all objects which have changed 
since your last update. If you want to display the most up-to-date information — like 
XenCenter does — then `event.from` is the way to go. We also had a lot of problems 
with the `event.next` queue overflowing, especially under heavy load (e.g. while starting 
lots of VMs). This caused `event.next` to return a lot of exceptions, which means you have to 
re-register for events and poll the current state of the objects again, adding even more load 
to the overloaded system.

I recommend using `event.from` if you can :-)

Cheers,
Dave Scott


I handle the pool syncing a little bit different, which is slower, bit a bit 
more straight forward:
1. event.register(*)
2. foreach($obj_types as $type) $type.get_all()
3. while($running) event.next()

Greetings
Uli Stärk

-----Ursprüngliche Nachricht-----
Von: xen-api-bounces@xxxxxxxxxxxxx [mailto:xen-api-bounces@xxxxxxxxxxxxx] Im 
Auftrag von tony_caotong@xxxxxxx
Gesendet: Mittwoch, 16. September 2015 04:39
An: xen-users@xxxxxxxxxxxxx; xen-api@xxxxxxxxxxxxx
Betreff: [Xen-API] value of timestamp from API event.from() is always '0'

Hi all,

     My xenserver version is 6.2
     When I fetch logs from API function event.from(), the value of each 
timestamp field is always '0.' .
     Instead of event.next(), it is fine.
     Could anyone give me some advices ?

--
-----------
Cao Tong



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